Field of the Invention
The present invention relates to a resist under layer film composition to be used in a multilayer resist step which is used for a fine processing in a manufacturing step of a semiconductor apparatus, etc., or an organic film composition effective for a planarizing composition for manufacturing a semiconductor apparatus, a process for forming a film using the same, a patterning process using the organic film composition suitable for exposure by using a far ultraviolet ray, a KrF excimer laser (248 nm), an ArF excimer laser (193 nm), an F2 laser (157 nm), a Kr2 laser (146 nm), an Ar2 laser (126 nm), a soft X-ray (EUV), an electron beam (EB), an ion beam, an X-ray, or the like, and a compound useful as a component of the organic film composition.
Description of the Related Art
As an LSI advances toward higher integration and higher processing speed, miniaturization of pattern size is rapidly progressing. In accordance with this miniaturization, the lithography technology therein has achieved formation of a fine pattern by shifting the wavelength of a light source shorter and by proper selection of a resist composition for such a light source. The main stream of this is a positive photoresist composition used in a monolayer. In this monolayer positive photoresist composition, a resist mechanism is constructed such that a skeleton having an etching resistance to dry etching by a gas plasma of a chlorine type or a fluorine type is introduced into a resist resin, and that an exposed part thereof is dissolved, so that a pattern may be formed by dissolving the exposed part, and then a substrate to be processed which is coated with the resist composition may be dry etched by using the remained resist pattern as an etching mask.
However, if miniaturization is pursued without changing a film thickness of the photoresist film to be used, or in other words, if the pattern width thereof is made further smaller, the resolution performance of the photoresist film is lowered. And in addition, when the photoresist film is pattern-developed by a developer, a so-called aspect ratio thereof is so large that a phenomenon of the pattern collapse occurs. In view of the above-mentioned, film thickness of the photoresist film has been made thinner in accordance with this miniaturization.
On the other hand, for processing of a substrate to be processed, a method of processing this substrate by dry etching using a photoresist film having a formed pattern as an etching mask has been usually used. Practically, however, there is no dry etching method capable of providing a complete etching selectivity between the photoresist film and the substrate to be processed; and thus, during processing of the substrate, the resist film is also damaged and causes collapse of the resist film during the time of processing of the substrate so that the resist pattern cannot be transferred precisely to the substrate to be processed. Accordingly, the resist composition has been required to have a further higher dry etching resistance in accordance with finer patterning. Also, because of the shift of the exposure light to a shorter wavelength, a resin used for the photoresist composition is required to have a smaller light absorbance at the wavelength of the exposure light, so that, in accordance with the shift to i-beam, KrF, and ArF, the resin has been shifting to a novolac resin, polyhydroxystyrene, and a resin having an aliphatic polycyclic skeleton. Practically, however, the etching rate under the dry etching condition mentioned above is increasing so that recent photoresist compositions having a high resolution tend to have rather a lower etching resistance.
In the situation as mentioned above, a substrate to be processed must be dry etched by using a photoresist film having a thinner thickness and a lower etching resistance than ever; and thus, securement of a material in this process and a process itself has become imperative.
A multilayer resist process is one of solutions for these problems. This process is as follows: a middle layer film having a different etching selectivity from a photoresist film (that is, a resist upper layer film) is set between the resist upper layer film and a substrate to be processed, and then, to obtain a pattern on the resist upper layer film; the pattern is transferred to the middle layer film by dry etching by using the resist upper layer film pattern as a dry etching mask; and then the pattern is transferred to the substrate to be processed by dry etching by using the middle layer film as a dry etching mask.
The multilayer resist process further include a three-layer resist process which can be performed by using a typical resist composition used in a monolayer resist process. For example, this three-layer resist process is configured to form: an organic film based on novolac resin or the like as a resist under layer film on a substrate to be processed; a silicon-containing film as a resist middle layer film thereon; and a usual organic photoresist film as a resist upper layer film thereon. Since the organic resist upper layer film exhibits an excellent etching selectivity ratio relative to the silicon-containing resist middle layer film for dry etching by fluorine-based gas plasma, the resist upper layer film pattern is transferred to the silicon-containing resist middle layer film by means of dry etching based on fluorine-based gas plasma. Further, since the silicon-containing resist middle layer film exhibits an excellent etching selectivity ratio relative to an organic under layer film in the etching using an oxygen gas or a hydrogen gas, pattern of the silicon-containing middle layer film is transferred to the under layer film by means of etching based on an oxygen gas or a hydrogen gas. According to this process, even when a resist composition which is difficult to form a pattern having a sufficient film thickness for directly processing the substrate to be processed or a resist composition which has insufficient dry etching resistance for processing the substrate is used, pattern of the organic film (resist under layer film) of novolac resin and so on having a sufficient dry etching resistance for the processing can be obtained when the pattern can be transferred to the silicon-containing film (resist middle layer film).
While numerous materials have been known (for example, Patent Document 1) for the organic under layer film as described above, in recent years, it has now been growing necessity to have excellent filling and planarizing characteristics in addition to dry etching resistance. For example, when a ground substrate to be processed has a fine pattern structure such as a hole or a trench, it is necessary to have filling property which fills the pattern with a film without any voids. In addition, when the ground substrate to be processed has a step(s), or when a pattern dense portion and no pattern region exist on the same wafer, it is necessary to planarize the film surface by the under layer film. By planarizing the surface of the under layer film, fluctuation in the film thickness of a middle layer or a photoresist formed thereon is controlled, whereby a focus margin in lithography or a margin in the processing step of the substrate to be processed thereafter can be enlarged.
As a method of improving filling/planarizing characteristics of an under layer film composition, addition of a liquid state additive such as a polyether polyol has been proposed (Patent Document 2). However, the organic film formed by the method contains a large amount of the polyether polyol units, etching resistance of which are inferior, so that the etching resistance of the resulting film is markedly lowered whereby it is not suitable for an under layer film for the three-layer resist. Thus, it has been desired to develop a resist under layer film composition having both of excellent filling/planarizing characteristics and sufficient etching resistance, and a patterning process using the same.
Also, uses of an organic film composition excellent in filling/planarizing characteristics are not limited only to an under layer film for the three-layer resist, and it can be widely applied also as a planarizing composition for manufacturing a semiconductor apparatus, for example, planarizing a substrate prior to patterning by nano imprinting, etc. Moreover, for global planarizing during the manufacturing process of the semiconductor apparatus, a CMP process has now generally been used, but the CMP process is a high cost process, so that such a composition is expected to be a composition to serve the global planarizing method to be used in place of the CMP process.